FT2232D Async FT_Read problem

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Hello,

I am up and running with the FT2232D chip and software interface. I'm = putting it through the different modes and trying to pick the best one = for the intended harware. It looks like async bit-bang mode would be the = best, except for one thing. I will have external logic that streams data = to and from a PC via the FT2232D chip. The problem is that during a = asynchronous read cycle there is no indication from the FT2232 (via RD# = pin) as to when that data is actually read into the chip, so my external = logic does not know when to place the next byte of data onto the data = pins. During a read cycle the RD# pin is simply putting out the clocking = rate but is not representative of when the data is actually read. The = FT_Write cycle appears to provide this signal, but the FT_Read does not. = Is there anyway for my external logic to tell when the data is being = read into the FT2232D chip in asynchronous mode? I believe the = docmentation says that it should.

Thanks, Thomas

Reply to
Thomas Magma
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--
 Chuck F (cbfalconer at maineline dot net)
   Available for consulting/temporary embedded and systems.
Reply to
CBFalconer

A few more days of trying and I'm still pulling my hair out on this one. When I read from the FT2232 the RD# strobe pin appears to have no rhyme or reason to it. If I FT_Read in ten bytes of data the RD# pin will chaotically strobe several hundred times. The documentation says this is suppose to be useful to external logic...it makes no sense. However, when I FT_Write ten bytes of data the WR# pin strobes ten times perfectly in sync. FTDI is not getting back to me, does anyone have any suggestions?

Desperately, Thomas Magma

Reply to
Thomas Magma

Does seem strange, but these devices have many modes, so you would expect one to be able to 'pace' the bytes ?

FIFO mode would _have_ to do this, or the fifos would overrun/underrun ?

Have you trawled their app notes for the closest one to what you need ?

What external logic do you have - a CPLD ?

-jg

Reply to
Jim Granville

Well, just to confuse everyone...the external logic I have is a FIFO. So all it needs to transfer it's data to a PC (via FT2322) is a read clock input. This increments it's internal address pointer and puts the next byte of data on the bus. So that is why it would be nice to have the FT2232 strobe it's RD# pin in sync with when it's reading data. I would be able to transfer data (from my FIFO) at the maximum speed of the FT2232, as of now I'm S.O.L. I've tried every other mode, async bit bang is very close to what I need, yet so far away. I wish FTDI would respond to me.

Thomas

Reply to
Thomas Magma

I noticed the two sets of RD/WR pins. Any chance you might be using the wrong RD? (No offense intended :-) Gary

Reply to
Gary Drummond

A logical suggestion, but believe me, I have a logic analyzer connected to every pin on the chip and have it trigger on anything that moves. (no offense taken)

Thomas

Reply to
Thomas Magma

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